It is the 31st millennium. Under the benevolent leadership of the Immortal Emperor, the Imperium of Man hasstretched out across the galaxy. It is a golden age of discovery and conquest. But now, on the eve of victory, the Emperor leaves the front lines, entrusting the great crusade to his favourite son, Horus. Promoted to Warmaster, can the idealistic Horus carry out the Emperor's grand plan, or will this promotion sow the seeds of heresy amongst his brothers?

Created in the Emperor's own image, the primarchs had long thought themselves to be princes of the universe and masters of their own destiny - they led the Space Marine Legions in glorious conquest of the galaxy, and no enemy of the Imperium could stand against them. However, even amongst this legendary brotherhood, the seeds of dissent had been sown long before the treacherous Warmaster Horus declared his grand heresy.

Perturabo - master of siegecraft and the executioner of Olympia. Long has he lived in the shadow of his more favoured primarch brothers, frustrated by the mundane and ignominious duties which regularly fall to his Legion. When Fulgrim offers him the chance to lead an expedition in search of ancient and destructive xenos weaponry, the Iron Warriors and the Emperor's Children unite and venture deep into the heart of the great star maelstrom that haunts Perturabo's dreams.

From the battlefields of Phall and Isstvan, to the haunted shadows of Terra itself - the greatest war in the history of mankind rages on. While the traitor Legions continue their campaign of terror across the galaxy, preparations are made for the defence of the Imperial Palace and the final, inevitable reckoning that must yet come between Horus and the Emperor....

Fell times have come to the galaxy. Cadia has fallen, destroyed by the onslaught of Chaos. A Great Rift in the warp has opened, and from its depths spew daemons and the horrors of Old Night. But all hope is not lost.... A hero, long absent, has returned, and with him comes the wrath of the Ultramarines reborn. Roboute Guilliman has arisen to lead the Imperium out of darkness on a crusade the likes of which has not been seen since the fabled days of the Emperor.